U.S. Pat. No. 4,289,327 discloses a mechanical air bag device in which a frangible lid seals a container having gas under pressure. The frangible lid is supported by a pressing lid in contact with a link mechanism. Upon impact, the link mechanism is released which, in turn, releases the pressing lid which permits the frangible lid to be fractured by the high pressure gas to inflate the bag.
U.S. Pat. No. 5,301,979 discloses a gas air bag inflator where an ignitor causes a piston to be driven forward to knock out a seal to release the gas.
U.S. Pat. No. 5,388,322 discloses an explosive driven piston that is used to drive out a seal to release gas.
U.S. Pat. No. 3,900,211 discloses a ceramic support tube which is destructed by means of a pyrotechnic charge. The ceramic element, prior to destruction, holds a poppet against the container opening. The web of the poppet which closes the container opening is fractured by the fluid pressure of the container when the ceramic element is destroyed by pyrotechnic charge and forced to the opposite end of the poppet.
These prior art devices are complicated and expensive. Some of them release toxic gases to the safety air bag.
The present invention provides a non-explosive pyrotechnic linear release device comprising a body within which, at a proximal end, a pyrotechnic comprised of a compressed gasless ignition powder is contained behind a support ram which extends forward from the distal end of the body to support-the sealed exit end of a pressure container which has been charged with a fluid, preferably air. The compressed pyrotechnic provides 20,000 psi pressure, for example, against the proximal end of the support ram while the fluid under pressure provides 8,000 psi, for example, against the sealed exit end of the pressure container. When the pyrotechnic is ignited by signal from an impact detecting element in the automobile during a crash, the pressure provided by the compacted pyrotechnic is dissipated, the support ram is then pushed proximally by the pressure from the pressure container and the exit end of the pressure container becomes unsealed and releases the fluid under pressure to the air bag or bags provided in the automobile.
The structure of the invention permits the use of the heat generated by the burning of the pyrotechnic to raise the temperature of the released gas. In this respect, heat transfer fins are provided around the proximal end of the body in the area where the gasless ignition powder is contained and ignited.
The in-line structure of the invention further permits the disposition of two or more chambers containing compressed gasless ignition powder, longitudinally displaced from one another and ignitable either together or in sequence or reverse sequence to provide one, two or three speeds at which the gas is released to the air bag; controlled by initiators activated by weight/size sensors in the vehicle and/or by vehicle temperature sensors. One of the chambers houses the compressed powder at the proximal end of the device behind a primary support ram, while a second chamber houses a second charge of compressed powder within the primary support ram behind a secondary ram which extends forward to support the sealed exit end of the pressure container. Separate initiators ignite the pyrotechnic in the separate chambers.